Summary
Brings OpenTimestamps directly into Claude and other MCP clients so you can prove a document existed at a specific time by anchoring its SHA-256 hash into the Bitcoin blockchain. The server exposes tools to stamp hashes against public OTS calendars, upgrade pending proofs once Bitcoin confirms them (typically 60 minutes but sometimes longer), and verify timestamps against actual blocks. Everything runs locally with no API keys, storing proofs in a SQLite database at ~/.ots-mcp/. Includes a watcher that monitors pending stamps and a scheduler you can install to auto-upgrade them. Useful when you need cryptographic proof of existence for contracts, code releases, or any file where timestamp integrity matters and you want Bitcoin's immutability backing it up.
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@otskit/mcp
OpenTimestamps MCP server - stamp, upgrade, and verify Bitcoin timestamps via AI agents.
Exposes a set of tools to any MCP-compatible agent so it can timestamp documents, monitor confirmation status, and verify proofs against the Bitcoin blockchain - all from a conversation.
This is an independent implementation of the OpenTimestamps protocol. It is not affiliated with, endorsed by, or maintained by the OpenTimestamps project.
Note on confirmation times: After stamping, a proof is
pendinguntil Bitcoin confirms it. Confirmations typically arrive within ~60 minutes, but can take several hours during network congestion. Useots-mcp watchorupgrade_timestampto monitor. A pending proof is not a failed proof.
Install
npm install -g @otskit/mcp
Agent setup
ots-mcp setup claude # Claude Desktop
ots-mcp setup claude-code # Claude Code CLI
ots-mcp setup codex # Codex CLI
Each command writes the MCP entry into the agent's config file, makes a .bak backup if the file already exists, and skips if ots-mcp is already configured. Restart the agent afterwards to apply the changes.
CLI commands
| Command | Description |
|---|---|
ots-mcp serve | Start the MCP server (stdio transport) |
ots-mcp stamp <sha256> | Stamp a SHA-256 hash against Bitcoin calendars |
ots-mcp upgrade <id> | Check if a pending stamp has been confirmed |
ots-mcp verify <id> | Verify a stamp against Bitcoin |
ots-mcp list [status] | List stamps (pending / confirmed / failed) |
ots-mcp watch [minutes] | Monitor pending stamps and attempt due upgrades (default: 30 min, minimum: 15 min) |
ots-mcp check-pending | Run one upgrade pass over all pending stamps |
ots-mcp scheduler install|remove|status | Manage OS-level scheduler for auto-upgrades |
ots-mcp backup [dest] | Backup the SQLite database |
ots-mcp setup <claude|claude-code|codex> | Configure MCP for an agent |
MCP tools exposed to agents
| Tool | Description |
|---|---|
create_timestamp | Stamp a SHA-256 hash against 4 public OTS calendars |
upgrade_timestamp | Check if a pending stamp has been confirmed in Bitcoin |
verify_timestamp | Verify a stamp - proves hash existed before a given Bitcoin block |
verify_external_proof | Verify a whitelisted local file against its external .ots proof, without changing the local stamp store |
inspect_timestamp | Inspect a stored proof file without network calls |
list_pending | List stamps with status, retry count, and filters |
watch | Open a terminal window monitoring pending stamps and attempting due upgrades |
hash_file | Compute the SHA-256 of a local file and return it as a 64-char hex string (no network calls) |
stamp_file | Compute SHA-256 of a local file and stamp it on Bitcoin in one step |
Data directory
All data is stored in ~/.ots-mcp/:
~/.ots-mcp/
ots-mcp.db # SQLite database (stamps, proof files)
config.json # Optional config overrides
ots-mcp.log # Log file
Configuration
Create ~/.ots-mcp/config.json to override defaults:
{
"stamp_enabled": true,
"scheduler_interval_minutes": 30,
"retry_max_attempts": 20,
"calendar_timeout_ms": 10000,
"calendars": [
"https://alice.btc.calendar.opentimestamps.org",
"https://bob.btc.calendar.opentimestamps.org",
"https://finney.calendar.eternitywall.com",
"https://btc.calendar.catallaxy.com"
]
}
Development
npm run build # production build
npm run dev # watch mode
npm test # run tests
Dependencies
@otskit/client- OTS calendar client (brings in@otskit/core, the protocol engine)@modelcontextprotocol/sdk- MCP SDKnode-sqlite3-wasm- local database (pure WASM, no native compilation)
Requires Node.js >= 20.
Featured
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Download Free life-time →Notes, actions and memory. Without a meeting bot. First month 100% off.
Download for free →belt cli automatically finds the best tools and skills for your agent. image, video, music, tts...
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Get the MCP →Block distracting apps from your iPhone permanently without a 3rd party app. Free and open source.
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Registryactive
Package@otskit/mcp
TransportSTDIO
UpdatedJun 4, 2026
